A fuel cell system is an electro-chemical device that includes an anode and a cathode with an electrolyte therebetween. The anode receives a fuel such as hydrogen and the cathode receives an oxidant such as oxygen or air. When the hydrogen is supplied to a reaction plane of the anode, the hydrogen is ionized and the hydrogen ions are transferred to the cathode via a solid polymer electrolyte membrane. During this process, electrons are generated and flow to an external circuit, providing DC (direct current) electric energy. As the air is supplied to the cathode, the hydrogen ions, electrons, and oxygen in the air react at the cathode and produce water. The water is exhausted from the fuel cell system by means of a cathode exhaust passage. Typically, not all of the water is exhausted from the cathode exhaust passage.
Back pressure valves, such as the two-position valve disclosed in commonly owned U.S. Pat. App. Pub. No. 20050186457, incorporated herein by reference in its entirety, are typically disposed in the cathode exhaust passage and control a pressure within the fuel cell system. If water remains in the vicinity of the back pressure valve and the fuel cell system is maintained in a low-temperature environment after the fuel cell system is shut off, water remaining in the cathode exhaust passage may freeze and form ice. The ice may contact the valve flap of the back pressure valve and prevent normal operation of the valve. When the back pressure valves are not operating normally, it may be difficult to restart the fuel cell system, which is undesirable.
It would be desirable to produce a back pressure valve for a fuel cell stack assembly, wherein the back pressure valve includes a flap that can be heated to facilitate a melting of ice that has formed on the valve flap, wherein an energy and a time that are required to bring the valve to normal operating condition are minimized.